This invention relates generally to injection molding and more particularly to a two-piece nozzle seal which is seated in the front end of a nozzle to bridge the insulative air space between the heated nozzle and the cooled mold.
One piece nozzle seals and gate inserts having various configurations to be seated in the front end of a heated nozzle are well known. The applicants' U.S. Pat. No. 4,043,740 which issued Aug. 23, 1977 shows a nozzle seal which fits into a matching seat in the front end of the nozzle and has a portion which tapers inwardly around the gate. U.S. Pat. No. 4,981,431 to Schmidt which issued Jan. 1, 1991 discloses a nozzle seal having an outer sealing flange which is screwed into place in a seat in the front end of the heated nozzle. The applicants' U.S. Pat. No. 4,875,848 which issued Oct. 24, 1989 describes a gate insert which is also screwed into place, but has an integral electrical heating element U.S. Pat. No. 5,028,227 to Gellert et al. which issued Jul. 2, 1991 relates to a gate insert having a circumferential removal flange to allow it to be pried out of place in the seat in the front end of the nozzle. While these previous nozzle seals are satisfactory for many applications, when molding materials having a narrow temperature window such as Polyethylene Terephthalate (PET) it is very desirable to provide faster heat transfer along the nozzle seal without excessive heat loss to the surrounding cooled mold.